Around 13,000 people were evacuated from their homes on Wednesday night after sections of the main embankment of China's Yellow River collapsed, allowing the icy waters to inundate the surrounding countryside, said a flood control official on Thursday.

The bank bursts occurred at the river's main embankment in Erdos City, 250 km from regional capital of Hohhot.

Police forces were dispatched to help with the evacuation in Inner Mongolia Autonomous Region, but no casualties have been reported.

About 200 workers are constructing barriers of stakes and sandbags beside the embankments.

A 30-meter section of the embankment collapsed on Thursday morning, and a 450-meter stretch lower down burst on Wednesday afternoon, said Niu Shaoyun, deputy director of the flood control headquarters in Hangji Banner, Ordos City.

"We estimate that a total of 40 km of the main embankments are in danger of further erosion as the river level continues to rise by nearly five centimeters an hour in some sections," said Niu.

Some 13,000 people in six villages on the southern bank had to be evacuated, he said.

The icy waters were flowing through the breaches at 1,450 cubic meters per second on Thursday, and some other sections of the embankment were holding water at dangerous levels, said Niu.

The flood control authorities planned to channel the flood through roadside trenches to a dry riverway, 17 km from the collapsed bank, he said.

The river's ice flow was the heaviest in 40 years. The course in Hangqi Banner, where the embankment collapsed, is holding 450 million cubic meters of water, 50 percent more than in a normal year.

In efforts to alleviate the flood caused by ice blockage, the region deployed its first ever water diversion on the river on March 10 through a main drainage canal in rural Hetao area to nearby Wuliangsu Lake.

Chinese artillery troops also blasted the Qingshuihe section, downstream of the collapsed section to clear accumulating ice blocks threatening lives and property on March 14.

The regional ice run prevention headquarters issued a warning of the dangers of bank collapses and flooding on Tuesday, as the river continued to thaw.

About 212 kilometers of the 720-km length of the Yellow River in Inner Mongolia began to melt on March 11, after a full thawing of the upper stretch in neighboring Ningxia Hui Autonomous Region, and the thaw had reached sections near Bayan Nur City on the northern bank and Erdos City on the south, according to the headquarters.

More than 70,000 people in the region have been organized for rescue and disaster relief efforts along the river.

(Xinhua News Agency, March 20, 2008)